High-speed fuel injection system



July 22, 1969 J BASSOT ETAL 3,456,628

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July 22, 1969 BASSOT ET AL HIGH-SPEED FUEL INJECTION SYSTEM 18 Sheets-Sheet 17 Filed April 11, 1967 r lint!!! July 22, 1969 J BASSQT ET AL HIGH-SPEED FUEL TN-TECTION SYSTEM 18 Sheets-Sheet 18 Filed April 11, 1967 W W W2 W5 [6. W5 mw um United States Patent Int. Cl. F02m 51/06; F0211 3/06 U.S. Cl. 123-32 33 Claims ABSTRACT OF THE DISCLOSURE Construction of high speed injectors, a special type switch mechanism for synchronizing the operation of the injectors to the angular position of a motor shaft, a unijunction transistor time delay circuit whose base and emitter voltages are varied in response to variations in different parameters, rapid switching bistable control circuits, which control the injection period in one state, damping circuits for the injector, circuits for transferring the electromagnetic energy liberated by current interruption in one injector coil to the next injector coil to be activated, and circuits for regulating a motor driving a generator to correspond to the voltage, current or power output of the latter.

Background of the invention The present invention relates to fuel injection systems, and in particular to fuel injection systems with electronic controls and the injectors used with said electronic controls.

It is known that use of fuel injection systems instead of carburetors for motors with controlled ignition results in a certain number of advantages which are based on the greater possibilities for regulation and for adaptation to the particular type of motor. It is thus possible to lower the fuel consumption, to increase the power, and above all to reduce the percentage of unburned matter in the exhaust gas, especially the carbon monoxide. This is of great importance in cities, where the air pollution reaches serious proportions. However, the use of conventional injection pumps as are known for diesel motors would lead to a very high price since these devices are extremely precise with very tight tolerances.

Attempts have been made to reduce these inconveniences by electronic control systems using monostable multivibrators for electromagnetic injectors. But these devices again present a certain number of difliculties as, for example, a very high price and a relatively sluggish operation. This is because the electromagnetic injectors only allow a very low injection pressure and their respouse time to electric signals is so long that it is impos sible to provide one injector for each cylinder in either director indirect injection. On the contrary, it is necessary to provide only one injector for several cylinders, which injects during a period which corresponds to the quantity of fuel required for all the cylinders. Obviously with such a system one loses almost all the advantages of the injection system as compared to carburetors.

Summary of the invention operation of each of said high speed injectors to a corresponding predetermined angular position of a motor shaft generate injection starting signals corresponding to each of said angular positions. These injection starting signals also serve as inputs to variable delay means, which generate end of injection signals after a time delay varying as a function of one or more motor or ambient parameters. Bistable control means, which switch from a first to a second state upon receipt of the injection starting signals, and back to the first state upon receipt of the end of injection signals, generate said injection control signals determining the length of the injection period while in said second state. These injection control signals are then coupled to the high speed injectors.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.

FIG. 1 is an overall diagram of the fuel injection systern;

FIG. 2 is a more detailed diagram of the injection system;

FIG. 3 is a sectional view of an injector to be used in this injection system;

FIG. 4 is a curve of the operating characteristics of the injector shown in FIG. 3;

FIG. 5 is a curve showing the opening of the injector pictured in FIG. 3 as a function of time;

FIG. 6 is a curve showing the fuel quantity injected as a function of time with an injector according to FIG. 3;

FIG. 7 is a diagram showing a switching mechanism used with the injection device:

FIG. 8 is an electrical diagram showing the bistable circuit controlling the injection;

FIG. 9 is a circuit diagram of the delay element of the injection system;

FIG. 10 is a diagram showing a mechanism for obtaining regulation as a function of pressure in the inlet tubes;

FIG. 11 is another embodiment of this regulating device;

'FIG. 12 is an electrical diagram showing the electronic bistable circuit and the delay element;

FIG. 13 is a diagram showing a distributor used with the injection system;

FIG. 14 is a sectional view of the distributor shown in FIG. 13;

FIG. 15 is a curve showing the duration of the injection as a function of a regulating voltage;

FIG. 16 is an electronic diagram of a manual device for enriching the fuel mixture when the engine is cold, connected with the delay element;

FIG. 17 is an electronic diagram for an automatic device for enriching the fuel mixture when the engine is cold, connected with the delay element;

FIG. 18 is an electronic diagram of an automatic device for enriching the fuel mixture when the engine is cold, combined with a device for enriching the fuel mixture as a function of the inlet air temperature;

FIG. 19 is an electronic diagram of a device connected to the gas pedal for allowing temporary enrichment of the fuel mixture;

FIG. 20 is an electronic diagram of a device for correcting the duration of the injection as a function of the rotational speed of the motor;

FIG. 21 is another embodiment of a device for correcting the duration of the injection as a function of the rotational speed of the motor;

FIG. 22 shows a curve showing the duration of injection as a function of the speed of rotation with the device shown in FIG. 20;

FIG. 23 is a curve showing the duration of injection as a function of motor speed with the device shown in FIG. 21;

FIG. 24 shows another embodiment of a device for correcting the duration of injection as a function of motor speed;

FIG. 25 is an electronic diagram showing a relaxation oscillator combined with a bistable circuit;

FIG. 26 is an electronic diagram of a circuit according to FIG. 25 combined with the delay element;

FIG. 27 is a general electronic diagram utilizing a relaxation oscillator as a regulating element;

FIG. 28 is a sectional view of a capacitor having a capacity which varies as a function of the manifold pressure;

FIG. 29 is a block diagram showing an electronic distributing arrangement device;

FIG. 30 is a circuit diagram of an arrangement according to FIG. 29;

FIG. 31 is a diagram showing an electronic circuit for protection of the power transistor;

FIG. 32 is another embodiment of the circuit shown in FIG. 31;

FIG. 33 is an electronic diagram for an arrangement permitting individual adjustment of the duration of injection;

FIG. 34 is a curve of the quantity of fuel injected, as a function of time, with an arrangement according to FIG. 33;

FIG. 35 is another embodiment of an electronic device permitting individual adjustment of the duration injection;

FIG. 36 is a general diagram of an injection device using thyratrons in the bistable circuit controlling the duration of the injection period;

FIG. 37 is a first arrangement for the recovery of magnetic energy;

FIG. 38 is a second arrangement for the recovery of magnetic energy;

FIG. 39 is a third arrangement for the recovery of magnetic energy;

FIG. 40 is a fourth arrangement for the recovery of magnetic energy;

FIG. 41 is a fifth arrangement for the recovery of magnetic energy;

FIG. 42 shows an arrangement for preventing overvoltages due to interruption of the injection control coil current;

FIG. 43 is the arrangement of FIG. 42, combined with an arrangement for the recovery of magnetic energy;

FIG. 44 shows an alternate method for recovery of magnetic energy;

FIG. 45 shows the current in the injector coil as a function of time, for the circuit of FIG. 44;

FIG. 46 is a circuit for varying the injection period of a diesel engine as a function of the output voltage of an alternator driven by the engine;

FIG. 47 is a diagram of the circuit for varying the injection period as a function of the power delivered by an alternator driven by the diesel engine;

FIG. 48 is a diagram of an injector designed for use in a diesel engine; and

FIG. 49 is a schematic diagram illustrating the interconnection of the circuits illustrated in FIGS. 12, 17, 18, 19, 20 and 32, providing one example of how the injection period for each injector may be controlled as a function of a plurality of motor parameters.

from a fuel tank 3 or by way of a feed pump 4, and pumps the fuel by way of filter towards the electromagnetic injectors numbered 7 to 10. The circuit has a pressure regulating discharge valve 6 and if necessary a mechanical or pneumatic back pressure accumulator 11.

The electrical and electronic circuitry is fed by a source of energy, generally the storage battery 13, which itself is connected in a conventional manner to a generator 14 by way of a conventional regulator 15. The power may be connected to the electronic circuitry by switch 16. This switch may be operated independently or it may be connected to the switch furnishing the power for the motor ignition. The control means 12, receives information regarding the angular position of the motor from a device 17 and transmits orders in the form of current pulses, to the injector 7 to 10 by way of the distributor 18, which itself is made dependent on the angular position of the motor by the device 19.

Devices 17 and 18 thus constitute distributing means for synchronizing the time of operation of each of the high speed injectors to a corresponding predetermined angular position of the crank shaft. The control device 12 delivers current pulses which have a fixed amplitude and a width varying linearly with the manifold pressure through the distributing means 18 according to a signal furnished by a device 20. The manifold pressure is hereinafter called the fundamental regulatory parameter,

It should be noted that the particular parameters used for regulation in the embodiment shown are used purely as illustrative examples and are not intended to 'be limiting on the system, since the system is capable of accommodating many other parameters also.

The current pulses furnished by the device 12 undergo, by way of the devices 21 to 26, corrections based on:

(a) The local atmospheric pressure transmitted by device 21, eventually incorporated into device 20.

(b) The motor temperature transmitted by device 22.

(c) The temperature of the inlet air transmitted by device 23.

(d) The speed of depression of the pedal controlling the opening of the butterfly valve, transmitted by device 24. This device plays the role of the acceleration pump in a conventional system having a carburetor.

(e) The value of the coefficient of the rate of introduction of air to the motor, a value which depends on the speed of the motor and on the shape of the manifold. This correction is transmitted by the device 25.

(f) The angular lead of lag of the injection which is transmitted by the device 26.

As was stated above the fuel pressure is delivered by the pump 1 which acts as a simple liquid compressor and has no part in determining quantities to be furnished. This pressure exists only at the pump and not in the injectors themselves, which can operate under several hundred bars (a bar is the international unit of pressure) of pressure. For economic reasons the operating pressure of the order of ten bars for indirect injectors and of the order of thirty bars in direct injections are used. In any case the pumps used are of conventional type as for example gear pumps.

Valve 6 and the accumulator 11 used in conjunction with piston or gear pumps permit a substantially constant injection pressure to be maintained. The pump may be driven either by the motor itself or by an electric auxiliary motor.

In a preferred embodiment, the pump 1 is a gear pump driven by an electric motor and the necessity for the accumulator 11 is eliminated. If the electric motor is used it may be energized automatically by a switch connected to the system which furnishes the voltage for the ignition system.

However, if the pump is driven directly from the motor itself, the accumulator 11 is generally necessary. The valve 6 which regulates the pressure may be of a classical pressure regulating type or may be an electrically controlled valve.

In the latter case a valve having a construction similar 

